JP6960900B6 - Robot arm - Google Patents

Description

The present invention relates to communication inside the robot arm.

Robots required for skillful handling of objects, such as industrial or surgical robots, may have an arm consisting of rigid elements connected in series with each other by a number of flexible joints. many. Such a joint may be of any type, but generally may be a rotary joint, or may be a combination of a rotary joint and a straight joint. The arm extends from a fixed or movable base and ends with a tool or attachment for the tool. The tool may be, for example, a tool for grasping, cutting, illuminating, illuminating or imaging. The final joint in the arm may be called a wrist. Such a list may allow movement only around a single axis, or may be complex or complex joints that allow rotation around multiple axes. As disclosed in the co-pending patent application PCT / GB2014 / 053523 of the present inventors, the wrist may include two roll joints in which the axis extends approximately longitudinally with respect to the arm. The axis may be separated by two pitch / yaw joints that substantially traverse the arm.

For surgical robots, there are many important criteria that influence the design of the distal joint of the arm.
1. 1. It is desirable that the arm, especially the distal part where the wrist is located, is small. This allows multiple such robotic arms to move in close proximity, thus further expanding the range of surgery that the arm can perform.
2. 2. The outer shape of the distal part of the arm is preferably circularly symmetric with respect to the length of the arm. This allows the distal portion to rotate longitudinally without the need for repositioning when in close proximity to another robot or some other device or patient.
3. 3. Since it is desirable for the joint to be able to transmit high torque, it is possible to carry a heavier tool and transmit high acceleration to the tip of the tool.
4. Since it is desirable that the joint be stiff and have little or no play or elasticity, it will be anchored there when the tip of the tool is positioned. The traditional way to minimize play is to specify at the expense of one or more gear elements, which requires a high level of maintenance and releases worn pieces of gear in the arm. May be
5. Since it is desirable for all joints to have position and force / torque sensors, the control mechanism can capture data from these sensors.
6. The distal portion of the robot arm should be as light as possible in order to reduce the force to be exerted by the joint more proximal of the robot arm.
7. A typical robot arm has a cable that powers its drive motor and possibly tools and feeds back signals from sensors such as position sensors, torque sensors and imaging sensors. The arm preferably includes a path through which such a cable passes inside the arm.

Many important criteria make it difficult to design an arm that best balances all requirements.

One peculiar problem is how to contact the arm's sensors and motor, for example, to a central control controller that may be separated from the arm. When the size of the arm is minimized, the communication path needs to be arranged so that the available space can be used efficiently.

There is a need for improved communication equipment for robotic arms.

According to the present invention, there is a composite joint between the first limb and the second limb, the second limb is a robot arm located on the distal side of the first limb, and the first rotation axis is provided. A coupler element connected to the first limb of the arm by a one-rotation joint and to the second limb of the arm by a second rotation joint having a second axis of rotation, and the first and second. The first and second rotation position sensors for detecting the configuration of the arm around each of the second joints, and the first and second rotation positions sensors for detecting the torque applied around each of the first and second joints. Two torque sensors, a control unit for controlling the operation of the arm, a first communication unit supported by the arm and arranged on the proximal side of the coupler, and a distance of the coupler supported by the arm. It is a second communication unit arranged on the position side, and each said communication unit encodes data of the first data format received from one or more said position sensors and / or torque sensors into a data packet, and said first. A communication unit capable of forwarding the packet to the control unit according to a packet-based data protocol different from the data format, the first position sensor relative to the first communication unit, the outer wall of the first limb. It is connected by a physical data link running in the unit, and data representing the position detected around the first joint is sent to the first communication unit for encoding, while the first torque sensor is the second communication. The unit is connected by a physical data link running in the outer wall of the second limb, and data representing the torque detected around the first joint is sent to the second communication unit for encoding.

The second position sensor is connected to the second communication unit by a physical data link running in the outer wall portion of the second limb, and data representing a position detected around the second joint is encoded. It may be sent to the second communication unit for use.

The second torque sensor is connected to the second communication unit by a physical data link running in the outer wall portion of the second limb, and data representing the torque detected around the second joint is encoded. It may be sent to the second communication unit for use.

The above or each physical data link may be an electrical cable.

Each communication unit may be able to hold the data received from the position sensor and / or torque sensor in a buffer and then transfer the data to the control unit.

The second communication unit may be connected to the control unit through the first communication unit.

The first limb may have a motor to drive movement around the first and second joints. The motor may be connected to the first communication unit by a physical data link in order to receive a command signal from the first communication unit.

The first and second axes may be perpendicular to each other. The first and second axes may intersect each other.

The first and second joints may be part of the list of robots.

According to the second aspect of the present invention, a single unit located on the distal side of the first limb and the first limb for jointly connecting the first limb and the second limb to each other around the axis of rotation. It is a robot arm including the second limb connected to the first limb by a rotary joint, and the arm controls a torque sensor for detecting torque around the joint and the operation of the robot arm. A control unit for control and a first communication unit supported by the arm and arranged on the distal side of the rotary joint encode data in the first data format received from the torque sensor into a data packet. The torque sensor includes the communication unit capable of transferring the data packet to the control unit according to a packet-based data protocol different from the first data format, and the torque sensor can be used with respect to the first communication unit. It is connected by a physical data link running along the two limbs, and is characterized in that data representing the torque detected around the joint is sent to the first communication unit for encoding.

A second communication unit received from the position sensor by a rotation position sensor for detecting the configuration of the arm around the rotation axis and the second communication unit supported by the arm and arranged on the proximal side of the rotation joint. It may further include a second communication unit capable of encoding data in one data format into a data packet and forwarding the data packet to the control unit according to a packet-based data protocol different from that of the first data format. .. The rotation position sensor is connected to the second communication unit by a physical data link running along the first limb, and data representing the configuration of the arm around the rotation axis is used for encoding. It may be sent to the second communication unit.

The second communication unit may be supported by the first limb.

It may further include a drive gear that is fixed to the second limb and rotatably attached around the axis of rotation and rotates with respect to the first limb. The position sensor may be fixed to the first limb and associated with a position scale fixed to the second limb.

The position sensor may be attached to the first limb and the position scale may be arranged around the axis of rotation.

The first communication unit may be connected to the control unit via the second communication unit.

The rotation position sensor for detecting the configuration of the arm around the rotation axis may be further included. The first communication unit encodes the data in the first data format received from the position sensor into a data packet, and the data packet is sent to the control unit according to a packet-based data protocol different from the first data format. It may be further possible to transfer. The rotation position sensor is connected to the first communication unit by a physical data link running along the second limb, and data representing the configuration of the arm around the axis of rotation is the first for encoding. It may be sent to one communication unit.

It may further include a drive gear that is fixed to the second limb and rotatably attached around the axis of rotation and rotates with respect to the first limb. The position sensor may be fixed to the drive gear and associated with a position scale fixed to the first limb.

The position scale may be arranged around the axis of rotation.

The first communication unit may be supported by the second limb.

It may further include a drive gear that is fixed to the second limb and rotatably attached around the axis of rotation and rotates with respect to the first limb. The torque sensor may connect the drive gear to the second limb.

Each physical data link may be an electrical cable.

Each communication unit may be able to hold the data received from the position sensor and / or the torque sensor in a buffer and then transfer the data to the control unit.

The present invention will be described with reference to the accompanying drawings.

Schematic of a surgical robot arm. The figure which shows the rotation axis in the list of the arm of FIG. 1 in more detail. The figure which shows a part of the 1st wrist mechanism seen from the distal side and one side. The figure which shows a part of the 1st wrist mechanism seen from the distal side and the opposite side. The figure which shows a part of the 2nd wrist mechanism seen from the proximal side and one side. The figure which shows a part of the 2nd wrist mechanism seen from the distal side and one side. The figure which shows a part of the 3rd wrist mechanism seen from the distal side and one side. The figure which shows a part of the 3rd wrist mechanism seen from the distal side and the opposite side. The figure which shows the 3rd wrist mechanism in the central longitudinal cross section seen from one side. The figure which shows the 3rd wrist mechanism in the central longitudinal section seen from the opposite side. The figure which shows the communication path in a robot arm. The figure which shows another arrangement of the communication path in a robot arm. The figure which shows the communication path in the limb of a robot arm separated by a rotary joint. The figure which shows the module of the end for a robot arm in a longitudinal section.

The wrist mechanism described below has been found to provide a compact and mechanically advantageous configuration for at least some of the robot's wrist joints, or for other applications.

FIG. 1 shows a surgical robot having an arm 1 extending from a base 2. The arm 1 includes a large number of rigid limbs 3. The limbs 3 are connected by a rotary joint 4. The recent limb 3a is connected to the base by a joint 4a. The limb 3 and the other limb 3 are connected in series by an additional joint 4. Listing 5 consists of four separate rotary joints. In Listing 5, one limb 3b is connected to the most distal limb 3c of the arm 1. The distal limb 3c has an attachment 8 for a surgical instrument or tool 9. Each joint 4 of the arm 1 provides information about the current configuration and / or the load at that joint with one or more motors 6 engineered to generate rotational motion at each joint 4. It has one or more positions and / or torque sensors 7. For clarity, only some of the motors and sensors are shown in FIG. The arm 1 may generally be the one described in the patent application PCT / GB2014 / 053523 which is pending at the same time by the present inventors. The attachment point 8 for the tool has (i) a configuration that allows the tool to be mechanically attached to the arm and (ii) electrical and / or optical output and / or data to and from the tool. Any one or more of an interface for communicating with (iii) and a mechanical drive for driving some movements of the tool can be optionally included. In general, the motor is preferably located proximal to the driving joint to improve weight distribution. As described below, the controller for the motor, torque sensor and encoder is arranged together with the arm. The controller is connected to the control unit 10 via the communication bus.

The control unit 10 includes a processor 11 and a memory 12. The memory 12 non-transiently stores software that can be executed by the processor so that the operation of the motor 6 is controlled so that the arm 1 operates as described herein. In particular, the software can control the processor 11 to drive a motor (eg, via an arranged controller) in response to input from the sensor 7 and input from the surgeon command interface 13. The control unit 10 is connected to the motor 6 to drive them according to the output generated by the execution of the software. The control unit 10 is connected to the sensor 7 to receive the detected input from the sensor and is connected to the command interface 13 to receive the input from the sensor 7. Each connection may be, for example, an electrical cable or an optical cable, or may be a wireless connection. The command interface 13 includes one or more input devices that allow the user to request movement of the arm in a desired manner. The input device may be, for example, a manually operable mechanical input device such as a control handle or a non-contact input device such as a joystick or an optical gesture sensor. The software stored in the memory 12 is configured to respond to these inputs and move the arm joints accordingly according to a predetermined control procedure. The control procedure may include a safety feature that adjusts the movement of the arm in response to command input. Therefore, in summary, the surgeon can control the robot arm 1 with the command interface 13 to move it to perform the desired surgery. The control unit 10 and / or the command interface 13 may be separated from the arm 1.

FIG. 2 shows the list 5 of robots in more detail. Listing 5 includes four rotary joints 300, 301, 302, 303. Such joints are arranged in series, including a rigid portion of the arm extending from one joint to the next. The most proximal joint 300 of the list connects the arm portion 4b to the arm portion 310. The joint 300 has a "roll" axis of rotation 304 oriented approximately along the limb 4b of the arm just proximal to the wrist joint. The next most proximal joint 301 on the list connects the arm portion 310 to the arm portion 311. The joint 301 has a "pitch" rotation axis 305 perpendicular to the axis 304 in all configurations of the joint 300 and the joint 301. The next most proximal joint 302 on the list connects the arm portion 310 to the arm portion 311. The joint 302 has a "yaw" rotation axis 306 perpendicular to the axis 305 in all configurations of the joints 301, 302. In some configurations of the list, the axis 306 is also perpendicular to the axis 304. The next most proximal joint 303 on the list connects the arm portion 311 to the arm portion 4c. The joint 303 has a "roll" rotating shaft 307 perpendicular to the shaft 306 in all configurations of the joints 302, 303. In some configurations of the list, the axis 307 is also perpendicular to the axis 305 and parallel to the axis 304 (preferably on the same straight line). It is desirable that the axes 305, 306 intersect each other, in order for this to provide a particularly compact configuration. The joints 300, 303 may be arranged so that the axes 304, 307 can pass through the intersection of the axes 305, 306 in some configurations of the list.

The designs in this list can be assembled in a relatively compact shape and do not have singularities in specific parts of the range of motion that can require excessively high velocities for individual joints. Other than that, it is advantageous in that it enables a wide range of movement from the tool attached to the attachment point 8 at the tip of the arm portion 4c.

3 and 4 show an example of a mechanism suitable for realizing a part of the list 5 of the arm 1 of FIG. 3 and 4 focus on the mechanisms corresponding to the joints shown in FIGS. 3 and 302 (as in FIGS. 5-10).

In the region of Listing 5, the rigid arm portions 310, 311 have a hollow outer shell or cases 310', 310 ", 311', which shell defines most of the outer surface of the arm. Along with, the outer wall of each shell is partially or completely enclosed and contains voids within which other components such as motors, sensors, cables and arms are housed. The shell is made of metal such as aluminum alloy or steel. Alternatively, it may be formed from a composite, for example a fiber reinforced resin composite such as resin reinforced carbon fiber, the shell constituting part of the rigid structure of the arm portion attached between the joints. May include a structural skeleton as described below with respect to the embodiment of FIG.

In FIGS. 3 and 4, for clarity, the shell of the arm portion 310 is shown in two portions 310'and 310 ", both of which are outlined and disassembled from each other. The shells of parts 4b and 4c are omitted, similar to the mechanisms associated with joints 300, 303. The shells of arm parts 311 are shown to be partial, i.e. most of which extend from the flat part 311'. ..

The shell of the arm part 310 (consisting of the shell parts 310'and 310') and the shell of the arm part 311 (extending from the flat part 311') are the two rotations shown by 20 and 21. They are movable around each other around the axes. They correspond to the axes 305 and 306 of FIG. 2. The axes 20 and 21 are orthogonal. The axes 20 and 21 intersect. The central coupler 28 is a central coupler 28. It is attached to the arm portion 310 by bearings 29,30. The coupler 28 extends between the bearings 29, 30; the bearings 29, 30 are relative to the coupler 28 around the shaft 20 and the arm portion 310. Except for allowing rotation, the coupler is fixedly held to the arm portion 310, thus defining a rotary joint corresponding to the joint 301 in FIG. 2, further the bearing 31 is distal. The side shell connector flat portion 311'is attached to the coupler 28. The bearing 31 couples the distal shell connector flat portion 311', except that it allows relative movement of the flat portion around the shaft 21 and the coupler. It is fixedly held at 28 and therefore defines a rotary joint corresponding to the joint 302 in FIG.

Two electric motors 24, 25 (see FIG. 4) are mounted on the arm portion 310. Such a motor drives the drive shafts 26 and 27 extending in the middle of the wrist mechanism. The shaft 26 drives rotation around the shaft 20. The shaft 27 drives rotation around the shaft 21. The drive shaft 26 ends at the distal end of the worm gear 32. The worm gear 32 is engaged with the bevel gear 33 fixed to the coupler 28. The drive shaft 27 ends at the distal end of the worm gear 34. The worm gear 34 is further engaged with a gear train generally indicated by 35, which is terminated by the worm gear 36. The worm-shaped pinion gear 36 is engaged with a hypoid bevel gear 37 fixed to the distal shell connector 311'.

The gear 33 is formed as a sector gear. That is, the working arc (defined by the arcs of its teeth in the examples of FIGS. 3 and 4) is less than 360 °.

The gear train 35 is supported by the coupler 28. The gear train 35 includes an input gear 38 that engages the worm gear 34. The input gear 38 is located on its axis of rotation with respect to the coupler 28 that perfectly matches the axis 20. This means that the input gear 38 can continue to engage the worm gear 34 regardless of the configuration of the coupler 28 with respect to the arm portion 310 around the shaft 20. A series of additional gears having a shaft parallel to the shaft 20 transmit drive from the input gear 38 to the output gear 39 on a shaft 40 parallel to the axis of rotation with respect to the carrier 28 but offset from the shaft 20. The shaft 40 ends with a worm gear 36. The shaft 40 extends parallel to the shaft 20. The gear of the gear train 35 is supported by the coupler 28 together with the shaft 40.

Next, the operation of the wrist mechanism will be described. With respect to the movement around the shaft 20, the motor 24 drives the shaft 26 and is operated so as to rotate with respect to the arm portion 310. This drives the bevel gear 33 so that the coupler 28 and the distal shell flat portion 311'rotate about the axis 20 with respect to the arm portion 310. With respect to the movement around the shaft 21, the motor 25 drives the shaft 27 and is operated so as to rotate with respect to the arm portion 310. This drives the bevel gear 37 so that the distal shell connector flat portion 311'rotates about the axis 21 with respect to the arm portion 310. When the drive shaft 26 is rotated, the coupler 28 is rotationally driven to cause a parasitic motion of the distal shell connector flat portion 311'around the shaft 21 while the drive shaft 27 is stationary. It will be confirmed that 38 also rotates with respect to the coupler 28. In order to prevent this, the arm control system 10 performs a compensatory operation of the drive shaft 27 in conjunction with the movement of the drive shaft 26 as necessary, and separates the movement around the shaft 21 from the movement around the shaft 20. It is configured to do. For example, when it is necessary to move the shells 310 and 311 relative to each other only around the axis 20, the motor 24 is operated to generate the movement, while at the same time, the motor 25 has the input gear 38 rotated with respect to the carrier 28. It is operated to prevent it from happening.

Various aspects of the mechanism shown in FIGS. 3 and 4 are advantageous in helping to make the mechanism particularly compact.
1. 1. It is convenient that the bevel gear 33 is partially circular, that is, its teeth do not include a perfect circle. For example, the gear 33 may be less than 270 °, less than 180 °, or less than 90 °. This means that at least a portion of the other bevel gear 37 is placed so that it intersects a circle that coincides with the gear 33 and has the same radius as the outermost portion of the gear 33 around the axis of the gear 33. It is permissible. This feature is particularly important in the list of types shown in FIG. 2, which helps reduce the scale of the spread of the composite joint and at the same time has a pair of roll joints and a pair of pitch / yaw joints between them. be. This is because this type of joint has redundancy between the pitch / yaw joints so that it can reach a wide range of positions at the distal end of the arm, even if movement around the axis 20 is restricted. ..
2. 2. It is more convenient for the component gear 33 to rotate about the shaft 20 when the carrier 28 rotates with respect to the closest arm portion 310, as opposed to the rotation about the shaft 21. This is because the component gear can also be cut to accommodate the shaft 40 that intersects the circle. As a result, space can be saved by locating the worm gear 36 on the opposite side of the bevel gear 33 with respect to the gear row 35. However, in other designs, the gear 37 can have a partially circular shape because the component gear can rotate around the shaft 21.
3. 3. It is convenient that the worm gears 32 and 34 are located on the opposite side of the shaft 20 with respect to the bevel gear 37. That is, there is a plane including the shaft 20 in which the worm gears 32 and 34 are arranged on one side and the bevel gear 37 is arranged on the other side. This helps to provide a compact packaging arrangement.
4. It is convenient that the worm gear 34 is located on the opposite side of the bevel gear 33 away from the worm gear 36 and / or the gear train 35 is located only on the opposite side of the bevel gear 33 away from the worm gear 36. This also helps to provide a compact packaging arrangement.
5. Conveniently, the gears 33 and / or the gears 37 are provided as bevel gears because they can be driven away from the worm gears located in the plane of their respective external radii. However, they may be worm gears 32, 34 or external tooth gears engaged to their outer surfaces by radial toothed gears.
6. Conveniently, the bevel gear 33 is arranged so as to intervene between the worm gears 32 and 34. This helps in the compact packaging of the motors 24 and 25.
7. Conveniently, the bevel gears and the worm gears connected to them can be hypoids or skew axes, such as Spiroid®. These gears allow for relatively high torque capacity in a relatively compact form.

5 and 6 show a second form of a list mechanism suitable for providing the joints 301, 302 in the list of the type shown in FIG.

As shown in FIG. 5, the wrist includes a pair of rigid outer shells 310'311' that define the outer surfaces of the arm portions 310, 311 of FIG. 2, respectively. 310'is more proximal in the shell. The arm portions formed by the shells 310'and 311' can rotate relative to each other about the axes 62 and 63, respectively, corresponding to the axes 305 and 306 of FIG. The axes 62 and 63 are orthogonal to each other. The axes 62 and 63 intersect. Shells 310', 311' define the outside of the arm in the area of the wrist and are hollow to accommodate the rotating mechanism and to secure space for cables and the like, as described in detail below. It is said that. The shell can be made from a metal, such as an aluminum alloy or steel, or a composite, such as a fiber reinforced resin composite such as resin reinforced carbon fiber. The shell constitutes the main rigid body structure of the arm portion attached between each joint.

FIG. 6 shows the same mechanism as viewed from the distal and unilateral sides, with the shell 311'removed for clarity.

The shell 310'is connected to the shell 311' by a cross-shaped coupler 64. The coupler has a central tube 65 extending approximately along the length of the arm and defining a duct through its center. The first arms 66, 67 and the second arms 68, 69 extend from the tube. Each shell 310', 311'is attached to the coupler 64 by a rotary joint such that it rotates about a single axis and is limited to movement with respect to the coupler. The first arms 66, 67 are attached to the shell 310'by bearings 70, 71, which allow rotation between the first arm and the shell 310' around the shaft 62. The second arms 68, 69 are attached to the shell 311'by bearings 72, 73, which allow rotation between the second arm about the shaft 63 and the shell 311'. The first bevel gear 74 is concentric with the first arms 66 and 67. The first bevel gear 74 is fixed to the coupler 64 and is rotatable with respect to one 310'on the proximal side of the two shells. The second bevel gear 75 is concentric with the second arms 68 and 69. The second bevel gear 75 is fixed to one of the distal sides 311'of the two shells and is rotatable with respect to the coupler 64.

The two shafts 76 and 77 control the movement of the composite joint. Such a shaft extends from one of the proximal sides of the shell 310'to the central region of the joint. Each shaft is attached to the shaft of its respective electric motor (not shown) at its proximal end, and the housing of such motor is secured within the proximal shell 310'. In this way, the shafts 76, 77 are driven by a motor and are rotatable with respect to the proximal shell 310'.

The shaft 76 and related motors operate movements about the shaft 62. The shaft 76 terminates at the distal end of the worm gear 78 that engages the bevel gear 74. The rotation of the shaft 76 causes the bevel gear 74 to rotate about the shaft 62 with respect to the shell 310'. The bevel gear 74 is fixed to a coupler 64 which in turn has a distal shell 311'. Therefore, the rotation of the shaft 76 causes the shells 310'and 311' to rotate relatively around the shaft 62.

The shaft 77 and its associated motors operate movements about the shaft 63. To do this, the bevel gear 75 must finally be driven using the worm gear 79 carried by the coupler 64. The rotation of the worm gear 79 can cause a relative rotation between the coupler and the distal shell 311'. To achieve this, drive is transmitted from the shaft 77 to the shaft supporting the worm gear 79 via a pair of gears 80, 81 supported by the coupler 64. The shaft 77 approaches the carrier 64 from the proximal side. Gears 80 and 81 are located on the distal side of the coupler. The shaft 77 passes through a duct defined by the tube 65 at the center of the coupler. To adapt to the movement of the coupler 64 with respect to the first shell 310', the shaft 77 has a universal or hook joint 82 along its length. The universal joint 82 is located on the shaft 62. Instead of the hook joint, the shaft may have another form of flexible connection, eg, elastic connection (which may be integral with the shaft) or constant velocity joint form.

This mechanism is capable of providing a particularly compact, lightweight and rigid drive device for the components of the mechanism to rotate around the shaft 62 and the shaft 63 without excessively restricting the movement of the shell. found. This makes it possible to accommodate both motors in the proximal shell and reduce the weight on the distal side.

Various aspects of the mechanism shown in FIGS. 5 and 6 are advantageous in helping to make the mechanism particularly compact.
1. 1. It is convenient for the bevel gear 74 to be partially circular, i.e. its teeth do not contain a perfect circle. For example, the gear 74 may be less than 270 °, less than 180 °, or less than 90 °. This means that at least a portion of the other bevel gear 75 is placed so that it intersects a circle that coincides with the gear 74 and has the same radius as the outermost portion of the gear 74 around the axis of the gear 74. It is permissible. This feature is particularly important in the list of types shown in FIG. 2, which helps reduce the scale of the spread of the composite joint and at the same time has a pair of roll joints and a pair of pitch / yaw joints between them. be. This is because this type of joint has redundancy between the pitch / yaw joints so that it can reach a wide range of positions at the distal end of the arm, even if movement around the axis 62 is restricted. .. As shown in FIG. 6, the bevel gear 74 has a smaller radius in a region not included in its teeth. The partially circular bevel gears of other embodiments may be formed in the same manner.
2. 2. Conveniently, the gear 74 and / or the gear 75 is provided as a bevel gear because it can be driven away from the worm gears located in the plane of their respective external radii. However, they may be worm gears 76, 79 or external tooth gears engaged to their outer surfaces by radial toothed gears.
3 . Conveniently, the bevel gears and the worm gears connected to them can be skewed axes, eg, Spiroid®. These gears allow for relatively high torque capacity in a relatively compact form.

7-10 show another form of the wrist mechanism. In these figures, the shells of the arm portions 310 and 311 are omitted to expose the structure within the arm portions. The proximal arm site 310 has a structural skeleton 100, which is schematically shown in some drawings. The distal arm site 311 has a structural skeleton 101. The arm portions 310 and 311 can rotate relative to each other about the axes 102 and 103 corresponding to the axes 305 and 306 in FIG. 2, respectively. The carrier 104 connects the arm portions 310 and 311 together. The carrier 104 is attached to the arm portion 310 by bearings 105 and 190. These bearings define a rotary joint around the axis 102 between the arm portion 310 and the carrier 104. The carrier 104 is attached to the arm portion 311 by a bearing 106. These bearings define a rotary joint around the axis 103 between the arm portion 311 and the carrier 104. The first bevel gear 107 centered on the shaft 102 is fixed to the carrier 104. The second bevel gear 108 around the shaft 103 is fixed to the arm portion 311.

Similar to the other mechanisms described herein, the carrier 104 is located inside the limbs 310,311.

Two motors 109 and 110 are fixed to the skeleton 100 of the arm portion 310. The motor 109 drives the shaft 111. The shaft 111 is rigid and is terminated by a worm gear 118 that engages the bevel gear 107. When the motor 109 is operated, the shaft 111 rotates with respect to the proximal arm portion 310 to drive the bevel gear 107, hence the coupler 104 and the arm portion 311 to drive the arm portion 310 around the shaft 102. Rotate against. The motor 110 drives the shaft 112. The shaft 112 has a worm gear 113 near the distal end that engages the bevel gear 108. To accommodate the movement of the bevel gear 108 with respect to the motor 110 as the coupler 104 moves around the shaft 102, the shaft 112 is splined with a pair of universal joints 114, 115 to accommodate axial expansion and contraction of the shaft 112. It is equipped with a coupler 116. The final portion of the shaft 112 is attached to the coupler 104 by a bearing 117.

It is convenient for the bevel gear 107 to be partially circular, i.e., whose teeth do not contain a perfect circle. For example, the gear 107 may be less than 270 °, less than 180 °, or less than 90 °. This means that at least a portion of the other bevel gear 108 is placed so that it intersects a circle that coincides with the gear 107 and has the same radius as the outermost portion of the gear 107 around the axis of the gear 107. It is permissible. This feature is particularly important in the list of types shown in FIG. 2, which helps reduce the scale of the spread of the composite joint and at the same time has a pair of roll joints and a pair of pitch / yaw joints between them. be. This is because this type of joint has redundancy between the pitch / yaw joints so that it can reach a wide range of positions at the distal end of the arm, even if movement around the axis 102 is restricted. ..

Conveniently, the gear 107 and / or the gear 108 is provided as a bevel gear because it can be driven away from the worm gears located in the plane of their respective external radii. However, they may be worm gears attached to the shafts 111, 112 or external tooth gears engaged to their outer surfaces by gears with teeth on their outer surfaces.

Conveniently, the bevel gears and the worm gears connected to them can be skewed axes, eg, Spiroid® shapes. These gears allow for relatively high torque capacity in a relatively compact form.

Various changes can be made to the mechanisms described above. The following are examples and are not limited.
-The axes corresponding to axes 305 and 306 do not need to intersect or be orthogonal.
-Bevel gears or their equivalents of external tooth gears do not need to be driven by worm gears. They can be driven by other gears.
-Any or both bevel gears may be component gears.
-In the above embodiment, the mechanism constitutes a part of the list for the robot arm. Such mechanisms may be used in other applications, such as other parts of the robot arm, robot tools, and non-robot applications such as control heads for cameras.

As described with reference to FIG. 1, each joint is provided with a torque sensor that senses the torque applied to the shaft of the joint. The data from the torque sensor is provided to the control unit 10 for use in controlling the operation of the arm.

9 and 10 show one of the torque sensors and its mounting arrangement in cross section. The torque sensor 150 measures the torque applied to the shaft 103 extending from the carrier 104 to the distal arm frame 101. As described above, the bevel gear 108 is fixed to the frame 101 and is rotatable about the axis 103 with respect to the carrier 104. The bevel gear 108 includes a gear portion 151 extending in the radial direction and a neck portion 153 extending in the axial direction, and the gear teeth 152 extend axially from the gear portion 151. The neck 153, the gear portion 151 extending in the radial direction, and the gear teeth 152 are integrated with each other. The inner and outer walls of the neck 153 are cylindrical. A pair of rollers or ball bearings 106,154 fit snugly around the outer wall of the neck. The bearing is located in the cup of the carrier 104 and holds the neck 153 at a position related to the carrier while allowing the carrier to rotate the bevel gear 108 around the shaft 103.

The torque sensor 150 includes a top flange 155 extending in the radial direction, a twisted tube 156 extending axially from the top flange 155, and a base 157 having a female thread formed at an end of the twisted tube 156 opposite to the top flange 155. , Is equipped. The top flange 155 is in contact with the gear portion 151 of the bevel gear 108. The top flange is fixedly held to the gear portion by bolts 158. The twisted tube 156 extends inward of the neck 153 of the bevel gear 108. The outer wall of the twisted tube has a cylindrical shape. The outside of the base 157 is configured with a spline structure that securely engages with the corresponding structure in the frame 101 so as to hold the two fixedly to the shaft 103. Bolts 159 extend through the frame 101 to the base 157 and clamp them together. Therefore, it is a torque sensor 150 that attaches the bevel gear 108 to the arm frame 101, and the torque applied to the shaft 103 is applied via the torque sensor. The twisted tube has a hollow interior and a wall that is thinner than the twisted tube 150. When torque is applied through the torque sensor, a slight torsional distortion of the torsion tube occurs. The distortion of the twisted tube is measured by a strain gauge 160 fixed to the inner wall of the twisted tube. The strain gauge forms an electrical output indicating twist, which represents torque with respect to the shaft 103. The strain gauge may be in another form, for example, an optical interference strain gauge that provides an optical output.

In order to obtain the most accurate output from the torque sensor, torque transmission from the bevel gear 108 to the frame 101 that bypasses the twisted tube 156 should be avoided. Therefore, it is preferable to reduce the friction between the neck 153 of the bevel gear 108 and the base 157 of the torque sensor. One possibility is to provide a gap between the bevel gear neck and both the base of the torque sensor and the twisted tube. However, this makes it possible to apply a shearing force to the twisted tube in the direction transverse to the shaft 103 and reduces the accuracy of the torque sensor by exposing the strain gauge 160 to anything other than the twisting force. Another option is to install bearings between the inside of the neck of the bevel gear 108 and the outside of the base 157 of the torque sensor. However, this substantially increases the volume occupied by the mechanism. Instead, the configuration shown in FIG. 8 has been shown to give good results. The sleeve or bushing 161 is provided in the neck 153 of the bevel gear 108 around the twist tube 156. The sleeve is sized to seamlessly contact the inner wall of the neck 153 and the outer wall of the twisted tube 156, and is cylindrical. The entire inner surface of the sleeve is in contact with the outer surface of the twisted tube 156. The entire outer surface of the sleeve is in contact with the inner surface of the neck 153. The sleeve is configured to apply a relatively small amount of friction between the neck and the twisted tube, for example the sleeve may be formed or coated with a low friction or self-lubricating material. The sleeve is made of a substantially incompressible material so that deformation of the torque sensor can be prevented under shear forces across the shaft 103. For example, the sleeve may be made of or coated with a plastic material such as nylon, polytetrafluoroethylene (PTFE), polyethylene (PE) or acetal (eg, Delrin®). Alternatively, it may be formed of a metal impregnated with graphite or a lubricant.

To facilitate assembly of the mechanism and to hold the sleeve 161 in place, the inner wall of the neck 153 of the bevel gear 108 is inward at 162 near the end away from the radially extending gear portion 151. It is stepped in a staircase pattern. When the sleeve 161 is placed between the neck 153 and the twisted tube 156 and the head 155 of the torque sensor is bolted to the gear portion 151, the sleeve is radial (between the twisted tube and the neck) and (of the torque sensor). It is held in a state of being connected to both the head direction (between step 162) on the inner surface of the head 155 and the neck 153 of the bevel gear. It is preferable that the inner diameter of the neck 153 in the region 163 beyond the step 162 is configured so that the inner surface of the neck in the region is separated from the torque sensor 150 and the friction torque transmission between the two is prevented. ..

Similar configurations can be used for the torque sensor for the other shaft 102 of the embodiment shown in FIGS. 7 to 10 and the torque sensor of the embodiment shown in the other figure.

Hall effect sensors are used to detect the rotational position of the joint. Each position sensor comprises a ring of fabric placed around one of the axes of rotation. The ring has a series of north-south poles that are regularly spaced and alternating. Located adjacent to the ring, it is equipped with multiple Hall effect devices that can detect the magnetic field and measure the position of the magnetic poles on the ring with respect to the sensor array to provide a multi-bit output that indicates the relative position. There is a sensor chip with a sensor array. The ring of magnetic poles is arranged so that each position of each joint is associated with a unique set of outputs from the pair of magnetic sensors within a range of 360 °. This may be achieved by providing a different number of poles on each ring to create a number of poles in which the rings are relatively prime. Hall effect position sensors using this general principle are known to be used in robotics and other applications.

More specifically, each joint is associated with a pair of alternately magnetized rings and associated sensors. Each ring is placed concentrically around the axis of each joint. The ring is fixed to the element on one side of the joint, while the sensor is fixed to the element on the other side of the joint, so that when the robot arm rotates around each joint, Relative rotational motion occurs between each ring and its respective sensor. Each individual sensor measures the position of the associated ring with respect to the sensor between the pair of magnetic poles. Which of the individual sensors on the pair of magnetic poles on the ring is above the sensor cannot be determined from the output of the individual sensors. Therefore, individual sensors can only be used in relative ways and require calibration at power up to know the absolute position of the joint. However, by using a pair of rings designed so that the number of pairs of poles in each ring does not have a common factor, measurements between the pair of poles from both sensors can be combined and calibrated. It is possible to calculate the absolute position of the joint.

Therefore, the magnetic ring acts as a position scale and determines the rotational position between the arm portions 310 and 311 around the axis of rotation. Each sensor may correspond to each position scale. A sensor for measuring the rotational position of the arm portion 311 with respect to the arm portion 310 around an arbitrary axis of rotation may correspond to a position scale arranged around the axis. Sensors and scales are placed on opposite sides of the related joints so that relative rotation occurs between the sensor and the corresponding position scale when the arms are articulated around the related joints. May be good. This makes it possible to measure the relative movement between two arm parts connected by a joint.

Magnetic rings and sensors are shown in FIGS. 7-10. Magnetic rings 200, 201 and sensors 202, 203 are used to detect the position of the joint that provides rotation about the axis 102. Positions are detected for joints that provide rotation about the axis 103 using magnetic rings 210, 211, sensors 212, and additional sensors (not shown). The magnetic ring 200 is fixed to the carrier 104 and attached to one side of the carrier. The magnetic ring 201 is fixed to the carrier 104 and attached to the other side of the carrier 104 with respect to the magnetic ring 200. The magnetic rings 200, 201 are flat, arranged perpendicular to the axis 102, and centered on the axis 102. The sensors 202 and 203 are fixed to the frame 100 of the arm portion 310. The sensor 202 is attached so as to be adjacent to the side surface of the ring 200. The sensor 203 is attached so as to be adjacent to the side surface of the ring 201. Cables 204 and 205 carry signals from sensors 202 and 203. The magnetic ring 210 is fixed to the carrier 104 and attached to one side of the carrier flange 220. The magnetic ring 211 is fixed to the carrier 104 and attached to the other side of the carrier flange 220 with respect to the magnetic ring 200. The magnetic rings 210, 211 are flat, arranged perpendicular to the axis 103, and centered on the axis 103. A sensor 212 and another sensor for rotation around the shaft 103 are fixed to the frame 101 of the arm portion 311. The sensor 212 is attached so as to be adjacent to the side surface of the ring 210. Another sensor is mounted adjacent to the side surface of the ring 211.

Therefore, in the arrangement of FIGS. 7-10, the rotation around each axis 102, 103 is detected by two multipole magnetic rings, each equipped with a corresponding sensor. Each sensor produces a multi-bit signal that represents the position of the closest pole on each ring relative to the sensor. By arranging the poles on the two rings to be relatively prime, the sensor output is a combination that indicates the configuration of the joint within the range of 360 °. This makes it possible to detect the rotational position of the joint within that range. Further, in the arrangement shown in FIGS. 7-10, the two rings associated with each joint (ie, rings 200, 201 on the one hand and rings 210, 211 on the other hand) are substantially relative to each other along the axis of each joint. It is arranged so as to be offset. The ring 200 is located near the bearing 190 on one side of the body of the carrier 104, while the ring 201 is located near the bearing 105 on the opposite side of the carrier 104. The ring 210 is located on one side of the flange 220, while the ring 211 is located on the other side of the flange 220. Each ring is made of a sheet of fabric that is flat in a plane perpendicular to the axis on which the ring is placed. Each pair of magnetic rings (ie, rings 200,201 on the one hand and rings 210,211 on the other) are spaced apart from each other along their respective axes by a distance greater than five times the thickness of the pair of rings. They are more preferably spaced apart from each other in the direction along their respective axes by a distance greater than 10 or 20 times the thickness of the pair of rings. Conveniently, the pair of rings may be on opposite sides of their respective joints, as well as the rings 200, 201. Conveniently, the carrier 104 with the pair of rings attached extends radially outward so that it is located in the radial arrangement between the rings when viewed in a plane containing their respective axes of rotation. There is. Thus, for example, the flange 220 is located radially between the ring 210 and the ring 211. Conveniently, each joint may be supported or defined by two bearings, may be located on one side of the joint along each axis, or may be located at an extreme position on the joint. The specific or each ring of the joint may overlap one of the bearings in a plane perpendicular to the axis. Conveniently, the sensor for the ring may be mounted on an arm portion articulated by a joint. The sensor may be mounted on the opposite side of the arm portion.

By separating the rings, the packaging of the joint and / or arm site to which the associated sensor is attached can be significantly improved. By separating the rings, there are more opportunities to place the rings in convenient locations, and the ability to separate the sensors can itself provide the benefits of packaging. The joint is preferably stiff enough relative to the number of magnetic poles on the ring so that twisting of the joint under load does not adversely affect the measurement. For example, the joint is preferably robust enough so that the elements of the joint are not twisted enough to cause changes in the magnetic transition in the sensor under its maximum rated operating load, even if they are spaced apart. .. This makes it possible to detect the direction in addition to the movement under all load conditions.

Thus, in the apparatus shown in FIGS. 7-10, by measuring the position of each sensor with respect to the corresponding scale placed around the associated axis of rotation, the sensors 202, 203, 212 are aligned with axes 102 and 103, respectively. The rotation position of the arm portion 311 with respect to the surrounding arm portion 310 is detected. In the above example, the scale is in the shape of a magnetic ring or tracks 200, 201, and 202, 203. In other words, the sensors 202 and 203 measure the rotational position of the arm portion 311 with respect to the arm portion 310 around the axis 102. It is done by measuring the position of those sensors with respect to the corresponding scales 210 and 211 where both scales 210 and 211 are located around the axis 102. The sensor 212 measures the rotational position of the arm portion 311 with respect to the arm portion 310 around the shaft 103 by measuring the sensor position with respect to the corresponding scale 211 arranged around the shaft 103.

The arm portion 311 is the distal side of the arm portion 310. The arm portion 310 is located proximal to the joint around axes 102, 103 shown in FIGS. 7-10.
As described in connection with FIG. 1, the data from the torque sensor and the position sensor are fed back to the control unit 10. It is desirable that such data be passed by a wired connection through the arm itself.

Each arm portion comprises a circuit board. FIGS. 7 to 10 show the circuit board 250 conveyed by the arm portion 311. Each circuit board contains a data encoder / decoder (eg, integrated circuit 251). The encoder / decoder converts the signal between the format locally used for each arm portion and the format used for data transmission along the arm. For example, (a) locally with respect to the arm site, the position sensor may return a position reading as it passes by magnetic pole transition, and the torque sensor may indicate an analog or digital signal indicating the currently sensed torque. May be returned, and the drive motor may request a pulse width modulated drive signal. On the other hand, for data transmission along the (b) arm, a general data transmission protocol, which is a packet data protocol such as Ethernet® , may be used. Therefore, the encoder / decoder receives data packets carried along the arm from the control unit 10 and interprets those data to form a control signal for any local motor, as well as locally detected data. Can be received, converted to a packetized format and sent to the control unit. The circuit boards provided along the arm may be connected to each other by a communication cable so as to allow communication from a relatively distal circuit board via a number of proximal circuit boards. ..

In general, it is desirable not to send data from one component of the arm to the component more distal to the arm. Doing so would include cables that run unnecessarily distally within the arm, increasing the weight distributed to the distal side. And since the circuit boards are connected to each other, once the data is sent to the relatively distal circuit board, the next most proximal circuit board will transfer the data in any way. To process.

However, it may also be desirable to reduce the number of cables through the joint. It can be difficult to properly position such cables so that they prevent them from being damaged by the range of motion of the joint and / or prevent the cables from interfering with the range of motion of the joint. .. In some situations, these two requirements may conflict, and proper cable placement means handling this conflict well.

In the following, a large number of cable arrangements for another embodiment of the robot arm and their connection to position and torque sensors that may be appropriate to handle this conflict well are described.

The first arrangement to describe is that shown in FIGS. 7-10.

The composite joint around the shafts 102 and 103 has a rotation position sensor 202 and 203 (for rotation around the shaft 102) and a rotation position sensor 212 (for rotation around the shaft 103). The sensors 202 and 203 are attached to the frame 100 of the arm portion 310 on the proximal side of the joint where the motion is measured by the sensor. The data from the position sensors 202, 203 is sent along the cables 204, 205 extending along the arm portion 310 on the proximal side of the sensor. The sensor 212 is attached to the frame 101 of the arm portion 311. The data from the position sensor 212 is sent along the cable to the circuit board 250 on the same arm portion. In either case, no data is passed to the element of the arm distal to where the data was collected.

The composite joint around the shafts 102 and 103 has a torque sensor 150 (for rotation around the shaft 103) and a torque sensor 191 (for rotation around the shaft 102). The data detected by the torque sensors 150 and 191 is conveyed to the circuit board 250 as it is by the flexible cable. In the circuit board 250, the encoder / decoder 251 encodes the detected data into, for example, an Ethernet® packet and transmits it to the control unit 10. Therefore, rather than being sent to the circuit board of the proximal arm portion 310 for coding, the data from the torque sensor is passed to the circuit board of the more distal arm portion for coding and then It is passed via a cable from the circuit board toward the distal direction along the arm.

Such an arrangement is shown in FIG. The arm portion 310 includes a circuit board 195 that receives data from the position sensor 202 and provides command data to the motors 109 and 110. The arm portion 311 includes a position sensor 212 and a circuit board 250 that receives data from the torque sensors 150 and 191. The circuit board 250 encodes the detected data and passes it to the circuit board 195 via the data bus 196, and the circuit board 195 transfers it to the control unit 10 via the link 197. The position sensor 202 is directly connected to the circuit board 195 by a cable. The position sensor 212 and the torque sensors 150 and 191 are directly connected to the circuit board 250 by a cable. The circuit board 250 and the circuit board 195 are connected by a data bus 196. The position sensor 212 and the torque sensors 150 and 191 are connected to the circuit board 195 via the circuit board 250 (and the data bus 196).

Therefore, in the arrangement shown in FIG. 11, both torque sensors 150 and 191 are connected by each data cable to the circuit board 250 located at the distal arm portion 311. One position sensor (sensor 212) is also connected to the circuit board 250 by a data cable. Then, one position sensor (sensor 202) is connected to the circuit board 195 arranged at the proximal side arm portion 310 by a data cable.

Various aspects of this arrangement may be advantageous in minimizing the number of cables traversing the joint while minimizing the number of components placed distally in the arm.

For example, measuring the'output'torque (the torque actually applied to the entire joint) rather than the'input'torque (the torque produced by the joint actuator (eg motor) before it is applied to the joint). Is often desired. This is because it may provide more precise control of the movement of the robot arm. Therefore, in the arrangement shown in FIGS. 7-10, the torque sensor 191 connects the drive gear 107 to the carrier 104, and the torque sensor 150 connects the drive gear 108 to the distal arm portion 311. The torque sensor 191 may be attached to both the drive gear 107 and the carrier 104. The torque sensor 191 may be attached to both the drive gear 108 and the distal arm portion 311. Therefore, the torque sensor 191 is arranged downstream of the gear 107. That is, the torque is sequentially transferred from the gear 107 through the drive train to the torque sensor 191 and then to the carrier 104. Similarly, the torque sensor 150 is located downstream of the gear 108. Therefore, the torque is sequentially transferred from the gear 108 through the drive train to the torque sensor 150 and then to the arm portion 311. Since the torque sensor 150 is arranged on the distal side of the drive gear 108, it is convenient for this torque sensor to be connected to the circuit board 250 held in the distal arm portion 311 through the data cable. .. This prevents the data cable of the torque sensor 150 from crossing the composite joint.

Also, the position sensor measures the actual output of the joint operation (eg, the relative position between the arm portions 310 and 311 around the joint) rather than the output of the joint actuator (eg, the rotational position of the shaft 111 and / or 112). Is often desired. This is because the measured joint position may provide input data for a more accurate control system than the measured position of the drive actuator used to drive the joint. To directly measure the position of the joint, each sensor is placed on one side of the joint and corresponds to each magnetic track or scale placed on the other side of the joint. When the arms are articulated around a joint, the relative rotational movement between the sensor and the corresponding scale is used to measure the position of the arm sites around the joint with respect to each other. These sensors communicate data representing the detected position around the joint via a data cable. That is, the sensor is a wired component attached to the data cable there. The position scale may be a wireless component, for example if the scale is a magnetic ring.

Therefore, the sensor 202 (measuring the position between the arm portion 310 and the carrier 104 around the axis 102) is located within the arm portion 310 and the sensor 212 (measuring the position between the carrier 104 and the arm portion 311). Is conveniently located within the arm portion 311. In other words, the sensor 202 is located proximal to the joint, the sensor 212 is located distal to the joint, and both the corresponding scales 200, 210 are located on the carrier 104. That is, the wired components are located on opposite sides of the joint and the wireless components are located on carriers that intervene between the wired components. In this way, the sensor 202 may be coupled to the local circuit board 195 via a data cable. Further, the sensor 212 can be connected to the local circuit board 250 via a data cable to prevent any data cable from passing through the joint.

In the arrangement shown in FIG. 11, the torque sensor 191 is connected to the circuit board 250 arranged in the distal arm portion 311. For some equipment, this may be the most convenient arrangement. However, in other equipment, it is more convenient (from a design and manufacturing point of view) that the sensor 191 is connected to the circuit board 195 arranged at the proximal arm portion 310 via a data cable. May be. This would require the data cable to cross a joint with a rotating shaft 102, but nonetheless, sensors and cables could be arranged in this way to adapt to the robot design or assembled during manufacturing into the robot. It may be physically easier to do.

FIG. 12 shows an example of this alternative device.

The proximal arm site 310 is shown connected to the distal arm site 311 through Listing 5. The proximal arm site 310 also includes a circuit board 195 located proximal to the joint. Both the position sensor 202 and the torque sensor 191 are directly connected to the circuit board 195 via their respective cables, and data is transferred from the sensor to the circuit board. The circuit board 195 encodes the data detected from the sensors 202 and 191 and transmits the data to the control unit 10 through the data link 197. The arm portion 311 includes a circuit board 250 located on the distal side of the joint. The position sensor 212 and the torque sensor 150 are directly connected to the circuit board 250 via each data cable. The circuit board 250 encodes the data detected from the sensors 150 and 212 and transmits the data to the circuit board 195 through the data bus 196. The data bus 196 therefore passes through the joint. Also, the sensors 202 and 212 are located opposite each other in the composite joint of Listing 5, and the sensors 202 and 212 are separated by the composite joint (and carrier 104).

The placement of position and torque sensors and their data cables within the robot arm has been studied for composite joints. However, the position and connection of the data sensor to the communication unit is also a consideration for rotary joints (joints with one degree of freedom).

FIG. 13 shows the placement of position and torque sensors in a robotic arm for a rotary joint that connects two adjacent limbs or arm portions.

In particular, the arm portion 501 is connected to the arm portion 502 through a single joint 503. The arm portion 502 is on the distal side of the arm portion 501. The joint 503 is a rotary joint having a single rotary shaft 504 (pointed into the page of this figure). This joint allows the arm portion 502 to be articulated to the arm portion 501. No other joint connects the arm portions 501 and 502 to each other. The motor 505 drives the drive shaft 506 to rotate about a vertical axis. The drive shaft 506 has a pinion-shaped shaft gear 507 attached to the end thereof in this example. The gear 507 engages the drive gear 508 (shown as a bevel gear in this example). The gear 508 is arranged around a shaft 504 and is rotatably attached to a rotating shaft (not shown) that matches this shaft. The gear 508 is fixed to the distal arm portion 502. When the motor 505 drives the shaft 506, the rotation of the shaft gear 507 drives the gear 508, rotating it around the rotating shaft 504, and in turn articulating the arm portion 502 to the arm portion 501 around the shaft 504. Let me.

The position sensor unit (totally shown by 511) measures the rotational position of the joint 503. The position sensor unit includes a sensor 512 and a corresponding position scale 513. The sensor 512 is located within the proximal arm portion 501. It may be attached to an element (eg, framework) within the arm portion 501. The position scale 513 is fixed to the drive gear 508 and placed around the axis of rotation 504 (in FIG. 13, only a portion of the scale 513 is shown for clarity). Therefore, if the sensors 512 and scale 513 are located opposite each other in the joint 503 and the arm portions 501 and 502 are articulated to each other around the axis 504 (ie, if the joint 503 is articulated). , It is designed to be moved relative to the rotation. The position scale 513 may be in the shape of a magnetic track or ring, as described above in connection with FIGS. 7-10. The position scale may work in the same manner as the magnetic ring 200, 2011, 2010, 212.

Position sensors and position scales are located opposite each other in the joint. As a result, it is possible to directly measure the joint position as opposed to measuring the position of the joint actuator output (such as the position of the drive shaft 506). This is advantageous because the measured joint position may be a more convenient input to the control unit 10 compared to the output of the joint actuator.

The torque sensor unit 514 measures the torque applied around the joint 503. The torque sensor may be installed on the rotating shaft of the drive gear 508. The torque sensor 514 may be arranged in the same manner as the torque sensors 150 and 191 and work in the same manner. The torque sensor 514 connects the drive gear 508 to the arm portion 502. The torque sensor 514 may be connected to both the gear 508 and the arm portion 502. Therefore, the torque sensor 514 may be arranged between the drive gear 508 and the arm portion 502. The torque sensor 514 is therefore downstream or distal to the gear 508 such that torque is continuously transferred from the gear 508 to the arm portion 502 through the sensor 514 when the joint 503 is articulated. Placed on the side. As mentioned above, such an arrangement allows the sensor 514 to measure the torque applied to the entire joint 503 as opposed to the output torque of the joint actuator. This is advantageous because the sensed value of the torque applied to the entire joint may provide a more accurate input to the control unit of the robot arm.

The robot arm includes communication units 509 and 510 having the shape of a circuit board. The communication unit 509 is arranged at the arm portion 501, and the communication unit 510 is arranged at the arm portion 502. The communication unit 509 is therefore proximal to the joint 503 and the communication unit 510 is distal to the joint 503. The communication units 509 and 510 are connected to each other by the data bus 517.

The communication unit 509 is connected to the sensor 512 by a data cable 515 extending along the proximal arm portion 501. The cable 515 may connect the sensor 512 directly to the communication unit 509. The data cable 515 transmits the detected position data of the joint 503 to the communication unit 509. The data may be referred to as raw data. The communication unit 509 encodes the detected data and transmits the detected data to the control unit 10 through the communications link 516. The communications link 516 may be a physical link such as a cable, or may be a data bus. The communication unit 509 may work in the same manner as the circuit board 195. In particular, the communication unit 509 may packetize the data sensed from the sensor 512 (eg, into an Ethernet® packet). Then, those packets may be transmitted to the control unit. The communication unit 509 may also provide command data for the motor 505. The command data may be sent through a physical link (eg, a cable) connecting the communication unit 509 and the motor 505 to each other.

The communication unit 510 is connected to the torque sensor 514 by a data cable 518 extending along the distal arm portion 502. The cable 518 may directly connect the torque sensor 514 and the communication unit 510. The cable 518 transmits the detected data (which may be referred to as raw data) of the torque applied to the entire joint 503 to the communication unit 510. The communication unit 510 may work to encode the detected torque data, similarly to the circuit board 250. The communication unit 510 encodes the detected torque data and then transmits the detected torque data to the communication unit 509 via the data bus 517. The coded detected torque data is therefore transmitted distally along the arm from the communication unit 510 to the communication unit 509. The torque sensor 514 is therefore connected to the proximal communication unit 509 through the distal communication unit 510.

Thus, in the arrangement shown in FIG. 13, the sensed position data is transmitted upstream of the joint 503, i.e., proximally (proximal to the joint 503). The sensed torque data, on the other hand, is transmitted downstream of the joint 503, i.e., distally (distal to the joint 503).

This arrangement allows the data detected by the position and torque sensors to be transmitted to the communication unit without the need for a data cable to carry the data through the joint 503. In this respect, this arrangement is advantageous. As a result, the transmission of data via bus 517 only to it through joint 503 is restricted.

Various improvements and alternatives to the embodiments shown in FIGS. 11-13 are feasible. Here is an example.

In FIG. 13, the position sensor 512 is connected by a data cable to the communication unit 509 supported by the proximal arm portion 501. This is because the sensor 512 is supported by the proximal arm portion 501 and the corresponding position scale 513 is supported by the distal arm portion 502. As a result, the sensor 512 and the scale 513 are located on opposite sides of each other in the joint 513. In an alternative arrangement, the sensor 512 may be supported by the distal arm site 502 and the corresponding position scale 513 may be supported by the proximal arm site 501. For example, the position scale is located around the axis 504 (as before) but is fixed to the arm portion 501 so that it can rotate around the axis 504 with respect to the arm portion 502 (and thus the drive gear 508). May be done. The sensor 512 may be fixed to the drive gear 508 and the arm portion 502. Therefore, these sensors and arm portions move relative to each other even when the joints 503 are articulated. When the sensor 512 is supported by the distal arm portion 502, it is convenient for the sensor to be connected to the communication unit 510 by a data cable running along the arm portion 502 rather than the communication unit 509. .. As a result, the data cable carrying the data sensed from the sensor 512 is also prevented from passing through the joint.

The cable connecting the sensor to the circuit board in the arrangement of FIG. 13 has been described as a data cable. The data cable may be an electric cable. Sensors and circuit boards may also be connected by other types of physical data links such as optical fibers.

The physical data links for each arrangement of FIGS. 11-13 can be arranged at various locations within the robot arm. In one set of examples, each arm portion, or limb, comprises a case forming an outer surface or wall portion of the arm portion. The physical data link may run inside the outer wall. In another set of examples, the physical data link may be attached to the outside of the outer wall. For example, each of them may be attached to the outer surface of the outer wall portion.

The arrangement of FIG. 13 has been described as including only one position sensor 512 and the corresponding position scale 513. The arrangement may include a position scale corresponding to a second sensor laterally separated from the sensor 512 and the scale 513 along the direction of the axis 504. This makes it possible to determine the angular position of the joint 504 without the need for a calibration step.

The position scale in FIG. 13 has been described as a magnetic track or ring. The ring is arranged around the axis 504. In another example, the position scale may be in the form of a resistant or conductive track placed around the axis 504. In this case, the sensor 512 may include a conductive wiper attached to the track. When the joint 503 is articulated, the wiper moves relative to the track. As a result, the resistance between a point on the track and the wiper changes as if the resistance were a function of the wiper position. The sensor then uses the measured resistance to determine the position of the wiper (and thus the joint 503).

The drive gear 508 and shaft gear 507 of FIG. 13 have been selected merely as an example for the description of the rotary joint. It will be appreciated that the sensor and data cable arrangements in FIG. 13 are applicable to other types of gearing used to articulate rotary joints. For example, the drive gear 508 may be a flat part gear, a bevel gear, a hypoid gear, or the like. The shaft gear 507 may be a flat part gear, a bevel gear, a worm, or the like.

As shown in FIG. 2, the arm portion 4c is supported by the arm portion 311 and is rotatable about the shaft 307 with respect to the arm portion 4c. FIG. 14 shows a cross section penetrating the module including the arm portion 4c. Such a module has a base 400 and a side wall 440 fixed to the base. The base 400 is attached to the end face 401 of the tip of the arm portion 311 (see FIG. 7). The arm portion 4c is generally indicated by 403. The arm portion 4c is rotatable with respect to the base 400 about a shaft 402 corresponding to the shaft 307 of FIG. Therefore, the arm portion 4c is attached to the side wall 440 by bearings 430, 431 that define a rotary joint between the side wall 440 and the arm portion 4c around the shaft 402.

The arm portion 4c has a housing 404 that houses its internal components. These components include a circuit board 405 and motors 406,407. The motors 406 and 407 are non-rotatably fixed to the housing 404. The housing 404 is freely rotatable with respect to the base 400 by bearings 430 and 431. The groove 408 runs inside the module to accommodate a communication cable (not shown) that runs from the circuit board 250 to the circuit board 405. The communication cable carries a signal, and when the signal is decoded by the encoder / decoder of the circuit board 405, the signal outputs a control signal for controlling the operation of the motors 406 and 407.

The motor 406 drives the rotation of the arm portion 4c with respect to the arm portion 311. Therefore, the motor 406 drives the rotation of the housing 404 with respect to the base 400. The base 400 has a central boss 410.

The types of torque sensors described in connection with FIGS. 9 and 10 are generally mounted on the boss 410. Such a torque sensor has an integral member including a base 411, a twisted tube 412, and a radially extending head 413. The base 411 of the torque sensor is fixed to the boss 410 of the base 400. Similar to the torque sensors of FIGS. 9 and 10, the sleeve 421 twists the torque sensor to protect it from shearing forces and reduce friction between the surrounding components, i.e. the base 400 and the torque sensor. It extends around the tube.

The internal tooth gear 420 is fixed to the head 413 of the torque sensor. The motor 406 drives a shaft 414 having a pinion gear 415. The pinion gear 415 is engaged with the internal tooth gear 420. Therefore, when the motor 406 is operated, the pinion gear 415 is rotationally driven, whereby the motor 406 rotates the arm portion 4c constituting a part thereof around the shaft 402. The resulting torque around the shaft 402 is transmitted to the base 400 via the torsion tube 412 of the torque sensor, allowing the torque to be measured by a strain gauge attached to the torsion tube.

An interface 8 for an attachment to an instrument is shown in FIG. The shaft 440 of the motor 407 is exposed in the interface for providing drive to the appliance.

The torque data from the torque sensors 411, 421, 413 are passed to the circuit board 250 of the arm portion 311 for coding. The rotational position of the arm portion 4c can be detected by a sensor 445 carried in the arm portion 4c, which sensor 445 detects a transition between the magnetic poles on the rings 446 and 447 mounted inside the housing 404. The data from the sensor 445 is passed to the circuit board 405 of the arm portion 4c for coding.

Motors that drive rotation around the joints 102, 103 are attached to the proximal side of those joints at the arm portion 310. As described above, this makes it possible to avoid the weight near the tip of the arm and improve the weight distribution. On the other hand, the motor that drives the rotation of the arm portion 4c is attached to the arm portion 4c rather than the arm portion 311. This can be a disadvantage as the motor 406 needs to be mounted more distally, but it has been found that this makes the arm portion 311 particularly compact. The motor 406 may be packaged within the arm portion 4c so as to be parallel to a motor (eg, 407) that provides drive to the appliance, i.e., across a common plane perpendicular to the axis 402. This means that the incorporation of the motor 406 into the arm portion 4c does not require the arm portion 4c to be substantially lengthened.

Instead of the toothed gear, the drive of the joint may be performed by frictional means.

Applicants thereby disclose any combination of each separate individual feature and two or more such features described herein, and such features or combinations of features are common to those of skill in the art. It is disclosed to the extent that it can be carried out under the present specification as a whole in the light of the knowledge of the art. It is irrelevant whether such features or combinations of features solve any of the problems disclosed herein, and such specific statements do not limit the scope of the claims. Applicants have indicated that aspects of the invention may consist of such individual features or combinations of features. In view of the above description, it will be apparent to those skilled in the art that various modifications can be made within the scope of the present invention.

Claims (15)

A robot arm having a composite joint consisting of a first rotation joint and a second rotation joint between the first limb and the second limb, and the second limb is on the distal side of the first limb.
The first rotation joint having the first rotation axis is connected to the first limb of the robot arm, and the second rotation joint having the second rotation axis is connected to the second limb of the robot arm. With the coupler element that is
A first and second rotation position sensor for detecting the configuration of the robot arm around each of the first and second rotation joints, and
The first and second torque sensors for detecting the torque applied around each of the first and second rotary joints, and
A control unit for controlling the operation of the robot arm and
A first communication unit supported by the first limb and arranged on the proximal side of the coupler element, and a second communication unit supported by the second limb and arranged on the distal side of the coupler element. The first and second communication units encode the data in the first data format received from one or more of the first and second rotation position sensors and the first and second torque sensors into a data packet. A second communication unit capable of forwarding the data packet to the control unit according to a packet-based data protocol different from the first data format, and the like.
The first rotation position sensor is connected to the first communication unit by a data cable running in the outer wall portion of the first limb, and data representing a position detected around the first rotation joint is for encoding. The first torque sensor is connected to the second communication unit by a data cable running in the outer wall portion of the second limb, and the first torque sensor is connected to the second communication unit around the first rotary joint. A robot arm in which data representing the detected torque is sent to the second communication unit for encoding. The second rotation position sensor is connected to the second communication unit by a data cable running in the outer wall portion of the second limb, and data representing a position detected around the second rotation joint is obtained. The robot arm according to claim 1, which is sent to the second communication unit for encoding. The second rotation position sensor is connected to the first communication unit by a data cable running in the outer wall portion of the first limb, and data representing the position data detected around the second rotation joint. The robot arm according to claim 1, wherein the robot arm is sent to the first communication unit for encoding. The second torque sensor is connected to the second communication unit by a data cable running in the outer wall portion of the second limb, and data representing the torque detected around the second rotary joint is encoded. The robot arm according to claim 1 to 3, which is sent to the second communication unit for use. The second torque sensor is connected to the first communication unit by a data cable running in the outer wall portion of the first limb, and data representing the torque detected around the second rotary joint is encoded. The robot arm according to claim 1 to 4, which is sent to the first communication unit for use. The electric cable is a data cable running in the outer wall portion of the first limb for the first communication unit and / or a data cable running in the outer wall portion of the second limb for the second communication unit. 5. The robot arm according to any one of 5. The data received by each of the first and second communication units from one or more of the first and second rotation position sensors and the first and second torque sensors is buffered in the first data format and the following: The robot arm according to any one of claims 1 to 6, wherein the data packet can be transferred to the control unit. The robot arm according to any one of claims 1 to 7, wherein the second communication unit is connected to the control unit through the first communication unit. The first limb has a motor for driving movement around the first and second rotary joints, and the first communication for the motor to receive a command signal from the first communication unit by a data cable . The robot arm according to any one of claims 1 to 8, which is connected to the unit. The robot arm according to any one of claims 1 to 9, wherein the first and second rotation axes are orthogonal to each other. The robot arm according to any one of claims 1 to 10, wherein the first axis and the second rotation axis intersect each other. The robot arm according to any one of claims 1 to 11, wherein the first and second rotary joints are a part of the list of the robots. The first limb and the distal side of the first limb are connected to the first limb by a single rotary joint for jointly connecting the first limb and the second limb around the axis of rotation. A robot arm including the second limb.
A torque sensor for detecting the torque around the single rotary joint and
A control unit for controlling the operation of the robot arm and
A first communication unit supported by the second limb and arranged on the distal side of the single rotary joint encodes data in the first data format received from the torque sensor into a data packet, and the first is described. 1 Includes the first communication unit capable of forwarding the data packet to the control unit according to a packet-based data protocol different from the data format.
The torque sensor is connected to the first communication unit by a data cable running along the second limb, and data representing the torque detected around the single rotary joint is used for encoding. A robot arm characterized by being sent to one communication unit. A rotation position sensor for detecting the configuration of the robot arm around the rotation axis, and
The second communication unit, which is supported by the robot arm and is arranged on the proximal side of the single rotary joint, encodes the data in the first data format received from the rotary position sensor into a data packet, and the data packet is described. It further comprises a second communication unit capable of forwarding the data packet to the control unit according to a packet-based data protocol different from the first data format.
The rotation position sensor is connected to the second communication unit by a data cable running along the first limb, and data representing the configuration of the robot arm around the rotation axis is the second for encoding. 2. The robot arm according to claim 13, which is sent to the communication unit. Further including the rotation position sensor for detecting the configuration of the robot arm around the rotation axis.
The first communication unit encodes the data in the first data format received from the rotation position sensor into a data packet, and the data packet is sent to the control unit according to a packet-based data protocol different from the first data format. It is even possible to transfer to
The rotation position sensor is connected to the first communication unit by a data cable running along the second limb, and data representing the configuration of the robot arm around the rotation axis is the first for encoding. 1 The robot arm according to claim 13, which is sent to the communication unit.

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